If the stack tracer (CONFIG_STACK_TRACER) is disabled, the
fgraph-filter-stack test blows chunks:
[8] ftrace - function graph filters with stack tracer [FAIL]
+ reset_tracer
+ echo nop
./ftracetest: 19: /home/michael/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc:
cannot create /proc/sys/kernel/stack_tracer_enabled: Directory nonexistent
Fix it by checking if the proc file exists before echoing to it. With
the patch applied it fails correctly with:
[8] ftrace - function graph filters with stack tracer [UNSUPPORTED]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
a05ffdce71